A number of chemical compounds termed "calcium antagonists" or "calcium blockers" are known. Representative compounds of this type are disclosed, for example, in U.S. Pat. Nos. 4,304,914 and 4,321,384. These calcium blockers have been found useful in the treatment of hypertension, cardiac arrhythmia, angina pectoris, and a variety of other cardiac disfunctions.
Certain dioxopyridopyrimidines are disclosed in German published patent application No. 27,38,153; see especially Example 43. The subject compounds differ from those of this German patent application principally in the methyl substituent on the 7-position.